On 28/11/2011 16:22, Leyne, Sean wrote: > Adriano, > >>> select char_length( SUBSTRING(col1 from 1 for 20)) from tbl_test >>> returns >> 20 so I was expecting index to work. >>> workaround >>> CREATE INDEX IDX1 ON tbl_test COMPUTED BY (CAST(SUBSTRING(col1 >> from 1 >>> for 20) as varchar(20))) >>> >> This issue depends if we're allowed to change SUBSTRING with constant >> length to describe the result with that length instead of the value one, like >> we do with *PAD. >> >> Accordingly to the standard, substring "should" be described as returning the >> same type of the value. > By "type" does the standard mean the basic data type as well as the length? > I mean the "max length". It always returns blob for blobs and varchar for others types.
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